TGF-β signaling is characteristic of the CMS4 CRC, and Notch drives epithelial TGF-β2 expression in KPN tumors.14 Since TGF-β1 is the most abundant isoform,17 we tested its role in KPN organoids, and in inhibiting T cell activation. The gene discussed is TGFB1; the disease is colorectal carcinoma.